The goal of the proposal is to exploit advanced optical recording methods to study the basic properties of retinal dendrites and the role they play in the collection, integration and processing of visual information. Dendrites are the most dominant feature of a retinal neuron;they cover more surface area and are functional more complex than any other neuronal component, yet they are the least understood. They are too small for routine electrical recording, but it is possible to record from dendrites optically using two-photon laser scanning fluorescent microscopy to excite a Ca2+ -dependent fluorophore and measure changes in the fluorescence signal in response to visual stimulation. The investigator is a pioneer in the use of this method and has demonstrated its unique ability to monitor signals from dendritic compartments too small to be recorded form in any other way. In this research optical recording will be used to study the mechanisms responsible for the generation of light-evoked dendritic Ca2+ signals and their spatio-temporal spread through the dendritic arbor. This includes determining the relationship between the properties of the Ca2+ signal and visual stimulus that evoked it under dark and light adapted conditions. The retina is an image processor that is made up of neurons whose function as computational units depends on their dendrites. Hence in order to replace an eye lost to disease or trauma with a prosthetic devise it is necessary to first know how the neurons work and this requires knowing how their dendrites work.